Molded plastic siding panels for exterior building walls are known in the prior art. These molded panels are made from synthetic thermoplastic polymers, including polypropylene, polyethylene, and various mixtures and copolymers thereof.
Laterally elongated molded plastic panels are nailed to a wall support surface in horizontal rows partially overlapping each other in order to provide a pleasing appearance combined with a water-resistant protective layer over the support surface.
The molded plastic panels are typically installed by nailing several adjacent courses to a wall support surface, starting with a bottom course. A lower marginal edge region of each panel in courses above the bottom course overlaps a panel in the course immediately below. Side marginal edge regions of each panel overlap side marginal regions of adjacent panels.
Various mechanisms have been proposed for interlocking lower marginal edge regions of the plastic panels with panels in the course immediately below. One disadvantage of prior art interlocking mechanisms is that when one panel is damaged and must be replaced, at least one other panel must also be removed. Accordingly, there still remains a need for a means for interlocking adjacent upper and lower regions of plastic panels that allows for removal and replacement of only a single panel without affecting the other panels.
Overlapping side marginal edge regions of adjacent plastic panels has also posed problems in the prior art. Because the panels are relatively long, locking the panels together in their side marginal edge regions may cause bowing after installation when the panels undergo thermal expansion. Thermal expansion contraction accompanying temperature changes may also fracture overlapped portions of the panels unless suitable accommodations are provided for panel movement.
The panels commonly include a plurality of rows of simulated wood shingles in which individual shingle elements are spaced apart by gaps of identical width. Because all panels are produced by a single mold, they have an identical appearance from panel to panel. This identical width of all gaps and the identical appearance from panel to panel have heretofore made more readily noticeable the spacings between elements of laterally adjacent panels accompanying temperature variations. Accordingly, there still remains a need for molded plastic panels that will camouflage any spacings accompanying thermal contraction and expansion.
A principal objective of the present invention is to provide a molded plastic panel having an interlock mechanism locking the panel firmly in place, yet still permitting replacement of the panel if it becomes damaged without removing or damaging adjacent panels.
A related objective of the invention is to provide a molded plastic panel having side marginal edge regions for interlocking laterally adjacent plastic panels without bowing or fracturing the panel during installation or upon thermal expansion and contraction.
A further objective of the invention is to camouflage spacings of varying width between adjacent panels resulting from thermal expansion and contraction.
Another objective of the invention is to provide a process for making a molded plastic panel including an attachment hem having at least one locking tab, without any through openings in the attachment hem behind the locking tab.
Additional objectives and advantages of the invention will become apparent to persons skilled in the art from the following detailed description.